A casement or an awning window generally refers to a sash that is attached to its frame by one or more hinges. The hinges can be located on any side of the sash and the frame though generally not on the lower edge of the sash and frame. In general, a casement window rotates along a vertical axis (the hinges of a casement window defining a vertical rotation axis), while an awning window rotates along a horizontal axis (the hinges of an awning window defining a horizontal rotation axis). Most casement and awning windows which employ the use of a crank lever or cam handle operator open outwardly so as not to interfere with the operator of the window.
In a casement or awning window, a lock system is generally provided on the non-hinge side where the window sash meets the window frame. In some configurations, a tie bar having at least one rivet is provided in the frame and at least one keeper is provided on the sash. When the window is in the closed position, the keeper is adjacent to the rivets. The window operator then moves the tie bar via a drive assembly causing the rivets to engage with the keeper. This engagement pulls-in the window sash to the window frame thus providing a sufficient seal between the frame and sash and locking the window.
However, due to variations in window manufacturing and in field installations, it has been observed that the engagement of the rivet with the keeper may not be as precise as possible resulting in a less than satisfactory seal between the frame and sash. Prior attempts have been made toward providing adjustability of the rivet or the keeper, such as disclosed in U.S. Pat. No. 6,651,389, said patent being hereby fully incorporated herein by reference. These prior attempts, however, have not been entirely satisfactory. Therefore, there still exists a need for a window lock system that allows for easy adjustment resulting in a satisfactory seal between the sash and frame.